In an apparatus which detects a specified pattern, a binarizing unit converts input image data to bi-level image data, and a storage device stores the converted bi-level image data. A pattern detection unit comprises a plurality of detectors which detect a specified pattern (for example, a circular pattern) independently of each other and in parallel to each other. Each of the detectors detects the specified pattern on a block different from those for the other detectors in the bi-level image data stored in the storage device. Then, one most probable block is selected among the blocks including the specified pattern, and careful image recognition is performed on the selected block.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An apparatus which detects a circular pattern in a document image to recognize a specified image, comprising: a binarizing unit which converts input image data to bi-level image data; a storage device which stores the bi-level image data converted by said binarizing unit; a plurality of edge detectors which detect an edge of a circle on each of a plurality of detection blocks in the bi-level image data stored in said storage device, wherein detection on the detection blocks is performed independently and simultaneously; a detection result decider of a circular pattern which decides a general detection result for each of the detection blocks based on results detected by the plurality of edge detectors; and a selector which selects a detection block of highest possibility of the existence of the circular pattern among a plurality of detection blocks wherein the circular pattern is detected by said detection result decider, wherein said selector selects the detection block of highest possibility based on the degree of a true circle, and the degree of a true circle is calculated by determining a center and a radius of a circular pattern based on the edge positions stored in said storage device, and by determining coordinates of a plurality of sample points on a circumference based on the determined center and radius wherein the sample points are edges stored in said storage device.
2. The apparatus according to claim 1 , wherein said edge detector overlaps the detection block and sums a number of specified pixels included in the edge detection block while moving in the detection block in a specified direction.
3. The apparatus according to claim 1 , further comprising a latch which holds the detection position of each detection block and said general detection result.
4. The apparatus according to claim 1 , further comprising a careful circle pattern detector which performs careful pattern recognition of the circular pattern only for the selected most probable detection block and decides a similarity with the reference image.
5. The apparatus according to claim 1 , wherein said edge detector comprises a black pixel edge detector which detects an edge of black pixel in the circular pattern in the block and a white pixel edge detector which detects an edge of white pixel outside the edge of the black pixel.
6. A method for detecting a circular pattern in a document image to recognize a specified image, comprising: converting input image data to bi-level image data; storing the converted bi-level image data; detecting, with a plurality of edge detectors, an edge of a circle on each of a plurality of detection blocks in the bi-level image data stored in said storage device, wherein detection on the detection blocks is performed independently and simultaneously; deciding a general detection result for each of the detection blocks based on results detected by the plurality of edge detectors; and selecting a detection block of highest possibility of the existence of the circular pattern among a plurality of detection blocks wherein the circular pattern is detected, wherein selecting the detection block of highest possibility is based on the degree of a true Circle, and the degree of a true circle is calculated by determining a center and a radius of a circular pattern based on the edge positions stored in said storage device, and by determining coordinates of a plurality of sample points on a circumference based on the determined center and radius wherein the sample points are edges stored in said storage device.
7. The method according to claim 6 , wherein said edge detector overlaps the detection block and sums a number of specified pixels included in the edge detection block while moving in the detection block in a specified direction.
8. The method according to claim 6 , further comprising holding the detection position of each detection block and said general detection result in a latch.
9. The method according to claim 6 , further comprising performing careful pattern recognition of the circular pattern only for the selected most probable detection block and determining a similarity with the reference image.
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December 28, 2000
January 6, 2009
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